I posted this on a different forum, but I'll try here too. I am creating a knee wall that will act as a railing as you go into my attic space. My question has been how to make this sturdy. I don't want a lot of wobble as you could imagine. My floor joists will run parallel to the wall and there is actually a joist directly beneath the placement of the wall. Ideas??

You could notch a few of your knee-wall 2x4's so they half-straddle the joists, then nail/screw/bolt them to the joist. This should be plenty strong. You would only need 1 or 2 of them for the run of the knee-wall. The rest could just nail to the bottom sill plate 2x4.

This is how the knee-walls were attached in my kitchen, but I tore 'em out! They were very sturdy.

I agree with Square Eye's solution from the earlier post. Cut blocks, screw them between the joists and your 2 X 4s can be screwed to the blocks. Beside being strong, they will prevent ceiling damage below-- attaching to one joist will allow that joist to twist and turn causing a crack in the ceiling.
Glenn

I will see what I can do when I am looking at the floor joist. But I think that since the placement of the wall is pretty well set....it will be difficult to use blocking because the joist runs directly under where I need the wall to be. So I may have to fir out the blocking so that I can keep the wall where it needs to be. Thanks for all the responses!